Thermoresponsive latch and setting mechanism therefor



Aug. 19, 1947. F. M KUNE THERMO-RESPONSIVE LATCH AND SETTING MECHANISM THEREFOR 2 Sheets-Sheet 1 vFiled Nov. 13, 1944 FRANK M /(U/VE Zmnentor (Ittornegs M THEREFOR Aug, 19, 1947. MCKUNE THERMO-RESPONSIVE LATCH AND SETTING MECHANIS Filed N0\ 15, 1944 I '2 Sheets-Sheet 2 FRANK Al /(um;-

Zmventor attorneys Patented Aug. 19, 1947 UNITED SAT 5 2,426,039 'rnsmvionEsroNsIvE LATCH AND sn'r- TING MECHANIS l t I THEREFOR 9 Claims.

This invention relates to improvements in a thermo-responsive latch and setting mechanism therefor and more particularly to a latch brake mechanism for use in connection with retaining doors, windows and the like, open during normal conditions, but automatically closable in the event of fire, and which mechanism is rapidly resettable merely upon a re-opening of the closure.

In the prior art, it has been Well known to control fire doors and the like by means of a locking mechanism comprising a fusible element which is destroyed upon the occurrence of a predetermined degree of heat to release the doo to close either by gravity, counterweights or springs. In

Patent No. 2,253,861, issued August 26, 1941, to

McKune and Kennedy, an alternative construction was disclosed in which was employed a thermo-responsive but infusible element, which released a Weight to permit the same to effect the dislodging of a locking dog interposed at the joint of two arms pivoted together, whereupon the arms would jack-knife and the door normally retained open, would close. This construction overcame the difficulty inherent with the fusible link, in that it eliminated the necessity of employing a skilled mechanic who would install such a link once it had been destroyed, and thus reset the door, since the construction of this patent-permitted manual re-setting of the mechanism by relatively unskilled mechanics when it was desired to retain the door in its normal open position. It was found that the prior mechanism did require attention during re-setting of the latch element, and this is considered to a degree unsatisfactory, since it would be obviously more desirable if the latching mechanism could be arranged so that the elements would automatically reset themselves merely upon the opening of the door without any personal attention by a person opening the door to the latch itself.

It was also found that with this prior thermally-responsive mechanism that the arrangement of parts was such that it was not particularly easy to shield the element from being disturbed by rodents, birds and the like. Bearing in mind that often for years On end and at least for many months at a time it is conceivable that this release mechanism would never be called upon to operate, and that it would merely remain static and unchanged during all of that time, it has been discovered that unde such conditions animals and birds have a tendency to deposit foreign material, material for nests and the like in such undisturbed locations. In order to prevent interference with the mechanical operation of such I vention, I provide for latching mechanism, screeningv or shielding is considered advisable to insure proper function-. ing of the parts.

Having in mind the defects of this and other prior art, it is an important object of my invention to provide a thermally-responsive latch and setting mechanism which'is capable of being automatically re-set upon placing of the closure normally to be held open in its normal held-open position.

Another object of my invention is the provision in a mechanism of the type described, of a compact and unified arrangement of parts which can be easily shielded and screened from unauthorized interference.

Still a further and more specific object of this invention is to provide, in a release mechanism as described, a weight to fall and dislodge a latching dog, which weight is raisable through the employment of cams and cam-actuated simple raising levers.

The foregoing objects and others ancillary thereto, I prefer to accomplish as follows:

According to a preferred embodiment of my indisposal between a door and its frame, for example, a pair of arms which are pivotally joined together said arms including means for attaching one to the door and the other to an adjacent portion of the frame. Specifically, there is a first arm, a second arm pivoted to the first arm, and a latching shoulder on the first arm with which a latching dog carried by an anvil lever mounted upon the second arm, engages to prevent relative pivotal movement of the two arms. A gravity operated hammer normally held in non-striking position by thermallyesponsive means is provided to operate upon the anvil lever to effect the dislodgement of the latching dog from its position against the latching shoulder of the first arm. Included in the arrangement is a lifting lever for raising the hammer to a poised position and cam-actuated means are provided for operating said lever to raise the hammer. Said means primarily comprise a cam carried by the first arm, a cam follower carried by the second arm, and a swingably mounted rider camming means connected mechanically to the cam follower and associated with the lifting lever so that when the rider is swung the lifting lever is moved about its pivotal mounting and the hammer is raised to a point where the thermo-responsive link engages and retains the hammer in non-striking position.' With such an arrangement, it is possible in event of fire, for the thermal link to expand and dislodge itself from its holding action upon the hammer, thereby permitting the hammer to fall and strike the anvil lever thus dislodging the latching dog and permitting the fire door to close. When the emergency has passed, and there is no longer present sufllcient heat to operate the thermal link, and it is desirable to reopen the fire door, all that anyone need do is to swing the door open, whereupon the camming means for lifting the hammer is set in operation, the hammer is raised, the thermal link engages it, the latching dog is forced into locking engagement with the latching shoulder and the door will remain open so that the useful purposes set forth above will have been accomplished.

The novel features that I consider characteristic of my invention are set forth with particularity in the appended claims. The invention itself, however, both as to its organization and its method of operation, together with additional objects and advantages thereof, will best be understood from the following description of a specific embodiment when read in connection with the accompanyin drawings, in which:

Fig. 1 is a plan view of my thermo-responsive latch and setting mechanism therefor;

Fig. 2 is an enlarged sectional view taken on line 22 of Fig, 1;

Fig. 3 is a plan view of a pivotal end portion of first arm;

Fig. 4 is a plan of the second arm;

Fig. 5 is an enlarged fragmentary view in elevation with portions shown in section for convenience of illustration of the re-setting mechanism of my latch;

Fig. 6 is a perspective view of a lifting lever;

Fig. 7 is a fragmentary view in elevation taken 11 line 1-! of Fig. 5 of the camming mechanism employed in connection with the lever of Fig. 6;

Fig. 8 is a perspective view of a liftin lever and the hammer of the dog releasing mechanism;

Fig. 9 is a perspective view of a supplemental locking member employed in connection with the anvil lever; and

Fig. 10 is a perspective view of the anvil lever with the dog associated therewith.

A thermo-responsive latch and setting mechanism to overcome the defects hereinbefore enuview of a pivotal end portion characteristics: it must be capable of being rapidly and accurately reset without the attention of a skilled mechanic; and it must also be capable of being shielded or screened easily and simply, to prevent unauthorized interference therewith. Accordingly, a preferred embodiment of my invention, referring to Figs. 1 and 2 of the drawings, is shown mounted between a portion of a frame F, and a door D, in the manner of an angular brace, whereby the door is retained away from the opening about which the frame F is mounted. The mechanism comprises the first arm I0 and the second arm I2 which have, respectively, pivot heads I I and I3 that are joined together in superpositioning and pivotal relationship by means of the bolt I4 to which is threadedly engaged the nut I5, as can be clearly seen in Fig. 2.

The pivot head I I has a notch I6 at one end of which is the latching shoulder IT. The mouth of notch I6 is shielded by blade I8, the inner face of which, on occasion, functions as a cam for alatch dog 20, which will be more fully described hereafter.

Upon the pivot head I3 of the second arm I 2,

thus engaged the pivotally mounted lever 24, having the anvil 25 on one end and the angularly disposed arm 25 on the other end carrying the latch dog 20. Also pivotally mounted upon pin 23, by which lever 24 is pivotally mounted, are paired legs 28, 28, by which the hammer 30 is supported.

Bi-metallic blade 32 is secured to the head I3 by means of the screw 33. This blade is so shaped and positioned as to engage, at its end, in notch 34 formed in one face of the hammer 30. When blade holds the hammer in the elevated position shown in Figs. 1 and 2. It will be obvious that when suificient heat is applied to the bi-metallic blade 32, a thermal stress will be induced in the same, whereby the end of the blade is dislocated from the notch 34 to permit the poised hammer 30 to descend. In its descent, the hammer 30 strikes the anvil 25, causing lever 24 to swing about the pivotal axis of pin 23, and thereby to draw the latching dog 20 from its latching engagement with the shoulder I'I; thereupon the joint between the first and second arms I 0 and I 2, respectively, breaks, and the door D can swing or be forced by counterweights or the like to a closed position in the frame F, where it Will remain until re-opened after the cause producing the heat which actuated blade 32 has been removed.

Re-setting of the mechanism, whereby the dog 20 is disposed against the shoulder I1 and whereby the hammer 30 is poised, is accomplished by a system of levers and actuators therefor, as follows: a medially pivoted lifting lever 40, mounted upon the pin M in the supporting post 42 which is attached to pivot head I 3, is positioned so that one end of the lever engages under the born 44 of one of the legs 23 of the hammer 38 when the opposite end 45 of the lever is depressed, so that the hammer will be raised.

Mechanism for operating lever 40 is carried by the first arm I 0 adjacent its joint with arm I2, and comprises a pivoted arm 46 mounted upon pin 41 that is supported by the upright arm 48 which, by means of base plate 49, is screwed to the arm I0. Arm 46 in conjunction with the depending arm 50 forms a bell lever which is actuated by cam follower link 52 slidably mounted in the guide 53, connected at 54 to the arm 50, and actuated by the camming surface 55 mounted upon the head I3 of arm I2 and carried thereby. Arm 5!] and arm 46, respectively, have camming jaws and BI which engage the outer end 45 of lever 40, and as they swing relative the same, by reason of their camming surfaces, tend to depress that end of the lever and thereby raise the hammer.

The bell crank, comprising arms 46 and 50, has a counter-weight 64, which serves to keep the cam follower 52 against cam 55 and to tend to elevate the camming jaws 60, 6 I.

An auxiliary lock for the anvil lever 24 during the poising of the hammer in the elevated position, is provided by the bar 10 slidably mounted in a keeper II and having the forked end 12 which is engaged by the outstanding side pin I3 of lever 40.

Each time the arms I0 and I2 are brought into approximate alignment, the setting of the mechanism and poising of the hammer is accomplished by the operation of the foregoing described mechanism. As the heads II and I3 rotate relative each other about the axis of pin I4, cam follower 52, riding upon camming surface 55, causes the I provide a pair of ears 22, between Wh Q is camming jaws 60, 6|, to descend, and in turn l2 collapse, the

cause the lever 40 to rise under horn 44 and to elevate the hammer.

Simultaneously with the elevation of the hammer, the pin 13 swings in an arcuate or curved path about the axis of pin M, thereby forcing the bar 10 under the anvil lever 24, which has been previously elevated.

The elevation of the anvil lever 24 is accomplished by the action of the internal face of cam blade l8 upon the locking dog 20 which is pressed inward as it approaches the rear of said Such action disposes dog 20 in notch [B where it is held due to the maintenance of elevation of the lever 24 by bar iii then being disposed thereunder.

Normally, the door is opened somewhat wider than it will normally be retained by the releasable bracing means and of course the hammer 39 will be raised somewhat higher than it will normally rest in a poised position. This extra height is suggested by dotted lines in Fig. 2. Thereafter when pressure is removed from the door and the mechanism is allowed to come to rest, the hammer 30 is held upward by the free end of blade 32, the bar 19 is withdrawn from under the anvil lever 24 through the action of the counterweight 64, which tends to raise the jaws formed by members 60 and BI, and consequently raise the outer end 45 of lever 40 and to depress its opposite end from under and out of the path of the legs 28 of hammer 3B. This movement of lever 49 would cause pin 13 to swing backward and to withdraw bar 10 from under the falling path of lever 26. The tendency of counter-weight B4 to raise the jaws formed by members 60 and El and thereby raise the outer end of lever 40 is resisted by bar 10, however, which is now caught underneath anvil lever 24. The friction between the top of bar 10 and the under surface of anvil lever 24 is suflicient to prevent the withdrawal of bar 10 from its position under lever 24 by the action of gravity on counterweight 64.

As soon as dog 20 comes into engagement with shoulder l1 pressure is exerted on dog 20 by shoulder H which, acting through arm 25 as a lever, causes the anvil lever 2 3 to rotate slightly about its own axis until the lateral play of the anvil lever about its pivot pin 23 is taken up. This slight rotation of the anvil lever 24 about its axis sufficiently reduces the contact pressure between the under surface of said lever and the upper surface of bar 1!] to permit counterweight 64 to effect the withdrawal of bar Hi from under lever 24. The anvil 25 doesnt then fall, however, because the tendency of the door to close keeps shoulder l1 and dog 2!) pressing together with sufficient force to maintain anvil 25 in its elevated position until struck by hammer 30.

In order to prevent the arms H3 and I2 from becoming overthrown past an approximately straight line, the stop 80 carried spaced apart from head II strikes into abutment against the shoulder 8! on the arm l2. When arms in and dog 20 passes inside the stop 82!, between it and head i I.

The arm I is pivotally mounted to the frame F by means of the bracket 83, and arm l2, which is extensible for purposes of adjustment by means of the screw 84, is pivotally connected to the door by means of bracket 85.

While I have shown and described particular embodiments of my invention, it will occur to those skilled in the art that various changes and modifications may be made without departing from the invention, and I therefore aim in the appended claims to cover all such changes and modifications as fall within the true spirit and scope of my invention.

Having thus described my invention, I claim: 1. A thermo-responsive latch and setting mechanism therefor, comprising: a first arm, a second 7 arm pivoted to said first arm, said first arm having a latching shoulder, an anvil lever pivotally mounted upon said second arm, a latch dog carried by said anvil lever and positioned to engage against said latch shoulder to prevent relative pivotal movement of said arms, a gravity operated hammer to strike said lever and effect withdrawal of the latch dog from behind said shoulder, thermally responsive means for holding said hammer poised in non-striking position, a lifting lever for raising said hammer'to the poised position, means to actuate said lifting lever upon movement of both said arms toward the latching position, said means comprising: acam carried by said first arm, a cam follower carried by said second arm in contact with said cam, a swingably mounted rider cam associated with said lifting lever, and means connecting said cam follower and said rider cam to move the same and actuate said lifting lever in raising said hammer.

2. A thermo-responsive latch and setting mechanism therefor, comprising: a first arm, a second arm pivoted to said first arm, said first arm having a latching shoulder, an anvil lever pivotally mounted upon said second arm, a latch dog carried by said anvil lever and positioned to engage against said latch shoulder to prevent relative pivotal movement of said arms, a gravity operated hammer to strike said anvil lever and effect withdrawal of the latch dog from behind said shoulder, thermally responsive means for holding said hammer poised in non-striking position, lever means for lifting said hammer to the poised position, means to actuate said lever means upon movement of both said arms toward the latching position, a cam carried by said first arm for urging said latching dog into engagement position with respect to said shoulder and for raising said anvil lever to the cocked position, and means movable with said lifting lever means for temporarily locking said anvil lever in its raised position, and means for returning said lifting lever means and said locking means to their normal inoperative positions upon the setting of the latch.

3. A thermo-responsive latch and setting mechanism therefor, comprising: a first arm, a second arm pivoted to said first arm, said first arm having a latching shoulder, an anvil lever pivotally mounted upon said second arm, a latch dog carried by said anvil lever and positioned to engage against said latch shoulder to prevent relative pivotal movement of said arms, a gravity operated hammer to strike said lever and efiect withdrawal of the latch dog from behind said shoulder, thermally responsive means for bolding said hammer poised in non-striking position, a lifting lever for raising said hammer to the poised position, means to actuate said lifting lever upon movement of both said arms toward the latching position, means for urging said latching dog into engagement position with respect to said shoulder while said arms are being moved to the latching position, and locking means to hold said latching dog in shoulder engagement position during the poising of the hammer and the setting of the latching dog against said shoulder.

4. A thermo-responsive latch and setting mechanism therefor, comprising: a first arm, a second arm pivoted to said first: arm, said first arm having a latching shoulder, an anvil lever pivotally mounted upon said second arm, a latch dog. carried by said anvil lever and positioned to engage against said latch shoulder to prevent relative pivotal: movement of said arms, a gravity operated hammer to strike said lever and effect withdrawal of the latch dog from behind said shoulder, thermally responsive means for holding said hammer poised in non-striking position, a lifting lever for raising said hammer to the poised position, a rider cam to actuate said lifting lever upon movement of both said arms toward the latching position, and means for urging said latching'dog into engagement position with respect to said shoulder While said arms are being moved to the latching position.

5. A thermo-responsive latch and setting mechanism therefor, comprising: a first arm, a second arm pivoted to said first arm, said first arm having a latching shoulder, an anvil lever pivotally mounted upon said second arm, a latch dog carri'ed by said anvil lever and positioned to engage against said latch shoulder to prevent relative pivotal movement of said arms, a gravity operated hammer to strike said lever and eifect withdrawal of the latch dog from behind said shoulder, thermally responsive means for holding said hammer poised in non-striking position, a lifting lever for raising said hammer to the poised position, a rider cam to actuate said lifting lever upon movement of both said arms toward the latching position, and a second cam carried by said first arm for urging said latching dog into engagement position with respect to said shoulder while said arms are being moved toward the latching position.

6. A thermo-responsive latch and setting mechanism therefor, comprising: a first arm, a second arm pivoted to said first arm, said first arm having a latching shoulder, an anvil lever pivotally mounted above said second arm adjacent its connection with said first arm, a latch do carried by said anvil lever and positioned to engage against said latch shoulder to prevent relative pivotal movement of said arms, a pivoted hammer arm astride said anvil lever and carrying a gravity operated hammer to strike said lever and effect withdrawal of the latch dog from behind said shoulder, thermally responsive means for holding said hammer poised in non-striking position, a lever pivoted laterally of said hammer arm for raising the same to poise the hammer, means forming a walled slot to engage and actuate said lever upon movement of both said arms toward the latching position said means forming a walled slot being carried by said first arm.

7. A thermo-responsive latch and settingmechanism therefor, comprising: a first arm, a second arm pivoted to said first arm, said first arm hav' ing a latching shoulder, an anvil lever pivotally mounted upon said second arm, a latch dog carsaid lever and positioned to engage prevent relative shoulder, thermally responsive means for holding said hammer poised in non-striking position, lever means for raising said hammer to the poised position, a rider cam carried to actuate said lever upon movement of both said arms toward the latching position.

8. In a thermo-responsive latch and setting mechanism therefor of the type including a pair of arms pivoted together and having a latching dog carried by one arm and a shoulder on the other arm with which the dog co-operates to reresponsive couple, a lever for lifting said hammer to the poised position, and a rider cam movable during the movement of the arms to the setting position to actuate said lever and raise said hammer.

pivot, one portion of said lever engaging said hammer for raising the same to poised position, and a cam operable upon the other portion of said lever for swinging the same about its pivotal mounting.

FRANK MCKUNE.

REFERENCES CITED The following references are of record in the file of this patent:

UNITED STATES PATENTS Date Aug. 26, 1941 Number 

